The present invention relates generally to an air handling structure and in particular to a horizontally oriented A-coil heat exchanger arranged in a housing forming a part of a central air conditioning system, with the coil being in series with the system blower. The A-coil heat exchanger or evaporator which in common practice is two evaporator slabs or plates, is connected at its apex by an air deflector or guide member as shown and described in U.S. Pat. No. 3,831,670--Mullings, assigned to the General Electric Company, assignee of the present invention. The air deflector member allows a smooth unrestricted flow of air to travel through the coils by allowing the air to remain closer to the center of the coil by pulling the air streams toward a parallel flow, thereby preventing the displacement of the air stream.
In the present invention, the A-coil heat exchanger is arranged so that the slabs are oriented generally horizontal relative to the flow of air. In operation of the air conditioning apparatus, all of the relatively warm air moves through the cooler heat exchanger, water vapor condenses out of the air and collects on the surfaces of the slab members.
When such condensation takes place, it generally collects on the surfaces of the coil, first as a light mist, and eventually attaining droplet size. These droplets generally collect on the lower portion of the heat exchanger and may present serious problems in the operations of the unit, and accordingly provision must normally be made for the collection and removal of the condensate from the system.
It has been discovered that condensate forming on a slab coil would tend to run downwardly along a seam of the slab structure and finally drop at its lowermost edge. Frequently therefore, a drain pan is provided at the lower level end of the heat exchanger to collect the condensate so that it may be evaporated off, or otherwise removed from the system. To be effective, the pan is generally positioned so that condensate may drip or run into it by the action of gravity.
In orienting an A-coil so that the slabs are generally horizontal with one coil arranged above the other as in the case of the present invention, the drip pan arranged on the lower edge of the heat exchanger while effectively collecting condensate from the lower portion of the lower coil, does not generally receive condensate from the upper coil during operation of the system blower. Since the condensate collected on the lower end of the upper coil is in droplet form or size, and with the air flow being generally at the rate of between 350 and 550 cubic feet per minute per ton of cooling capacity, the droplets would not fall down into the pan, but in effect would pick a course anywhere between horizontal and vertical and accordingly be blown out of the housing or atomized. It should be understood that condensate entrapped in the airstream may cause corrosive damage to the housing and may in some instances be carried out of the housing area to the electrical components of the system thereby causing a potential hazardous condition.
It is therefore an object of the present invention to provide an effective condensate collecting system for a horizontally oriented A-coil heat exchanger.
A further object is to provide an evaporator A-coil wherein substantially all of the condensate dripping from the upper slide is caught in a drip pan arranged below the lower slab.